JP3328558B2 - Metal surface treatment equipment by vacuum arc - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a oxidized film, dirt, and a coating film on a metal surface by causing a direct current arc discharge between an anode and a cathode in a vacuum or for modifying the surface of various metal surfaces. The present invention relates to an apparatus provided for a metal surface treatment by a vacuum arc for performing quality control.

[0002]

2. Description of the Related Art In metal surface treatment using a vacuum arc, an arc discharge is usually performed in an atmosphere of 10 ⁴ Pa to 1 Pa. Although it is called vacuum arc processing, it is not a processing technique in a strict sense of vacuum but a processing technique using an arc created in a reduced-pressure atmosphere. An arc formed in such a reduced-pressure atmosphere is referred to as a vacuum arc in accordance with the practice of the present invention. Vacuum arc is used for surface cleaning such as removal of oxide film (scale and rust) on metal surface, removal of oil and fat adhering to the surface, removal of coating film, and surface treatment such as roughening and heat treatment. ing.

In these metal surface treatments using a vacuum arc, a metal member to be treated is connected to a negative electrode of an arc power supply, and an arc is generated between the metal surface and a separately installed anode. The above-described surface treatment is performed by the action of the arc cathode spot formed on the surface of the processing target serving as the cathode.

One of the technical problems in vacuum arc processing is ignition of an arc. As is evident from the use of a vacuum atmosphere as a breaker of a power transmission system, it is difficult to generate an arc in a vacuum. Conventionally, as a method of reliably igniting in vacuum arc processing, an ignition electrode provided separately from an anode is instantaneously brought into contact with a metal to be treated as a cathode or an anode, and then separated to generate a spark on the ignition electrode. How to start and start the arc (Tokho 7-
No. 63689) or JP-A-6-26422.
As shown in Japanese Patent Publication No. 4 (1994), a high-frequency high voltage is applied between a firing electrode provided separately from an anode and a metal to be processed or an anode to generate a high-frequency spark at the firing electrode, thereby generating a high-frequency spark. As a starting point, a method of starting an arc between an anode and a metal to be treated as a cathode has been adopted.

Further, a metal surface local treatment apparatus using a vacuum arc devised by the present inventors (Japanese Patent Application No. 08-058762).
No.), it is difficult to put the ignition electrode in a vacuum vessel with a limited volume space. Therefore, by putting ceramics whose inner surface is coated with a conductive film into the vacuum chamber that creates a vacuum atmosphere, Without using electrodes,
The present inventors have proposed a method of enabling ignition by applying a high-frequency high voltage.

[0006]

As described above, one of the problems in the vacuum arc processing is to establish a technique for surely and easily starting a difficult arc. In the above-mentioned conventional start method of instantaneously bringing the ignition electrode into contact, or in the method of applying a high-frequency high voltage to the ignition electrode to generate a high-frequency spark, a special electrode is required. Is complicated and causes extra trouble, which leads to an increase in the cost of the apparatus and a decrease in the reliability of the work.

[0007] In addition, in the local treatment of a metal surface by a vacuum arc proposed by the present inventors, ignition becomes more difficult. Therefore, a ceramic covered with a new conductive film is used, and ignition is performed by applying a high-frequency high voltage. Have invented a method that allows Also in this method, when ceramics is used for the first time, there is an annoyance that the surface must be subjected to conductive processing. The present invention can reliably start the arc,
Another object of the present invention is to provide a metal surface treatment apparatus using a vacuum arc that does not require a complicated mechanism.

[0008]

The above object of the present invention can be achieved by an apparatus having the following configuration. (1) From the electrode, vacuum vessel, arc power supply and exhaust device
In the metal surface treatment apparatus according to the vacuum arc made, machine structure capable of superimposing a high-frequency high voltage to a DC voltage as the arc power supply
When the arc starts stably, high frequency high voltage is generated
A metal surface treatment apparatus using a vacuum arc, comprising: a mechanism for stopping the operation and providing only a DC voltage , and a power supply having a no-load voltage of 100 V or more; and (2) an electrode, a vacuum vessel, and an arc. From power and exhaust
A metal surface treatment apparatus using a vacuum arc
The container incorporates electrodes to provide adhesion to the workpiece
Cup-shaped vacuum vessel with a sealing material at the bottom
That the metal surface topical treatment apparatus according to the vacuum arc, machine capable superimposing a high-frequency high voltage to a DC voltage as the arc power supply
When the arc starts stably, high-frequency high-voltage is generated.
A metal surface treatment apparatus using a vacuum arc, comprising: a mechanism for stopping production and providing only a DC voltage ; and a power supply having a no-load voltage of 100 volts or more.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Under a vacuum atmosphere, when a voltage obtained by superimposing a high-frequency high voltage on a DC voltage is applied between a cathode and an anode, under what conditions the arc starts stably has not been studied so far. The present inventors have investigated in detail the relationship between the no-load voltage and the start of the arc,
When the no-load voltage was higher than a certain value, it was found that the arc started stably, leading to the development of the device of the present invention. In a vacuum atmosphere, only a small amount of resistance to the arc current exists in the space, so the arc maintenance voltage is lower than that in the atmospheric arc, and the voltage rating of the arc power supply is not regarded as important. Less expensive power supplies have been used. Therefore, a power supply having a high no-load voltage has not been used. Efforts have been made to increase the applied high-frequency voltage in order to ensure ignition, but this has not been successful as a stable ignition technique.

The present inventors superpose a high-frequency voltage on a high direct current no-load voltage between a metal to be treated, which is a cathode, and an anode to install a special ignition electrode, We found that reliable arc ignition was possible without using ceramics.

FIG. 1 shows the results of an investigation on the relationship between the ignition of a vacuum arc and the no-load voltage of an arc power supply. The measurement was performed using a metal surface local treatment apparatus using a vacuum arc shown in FIG. Steel material 1 was used as a cathode. A vacuum vessel is formed by the water-cooled body 2 and the detachable skirt 8, and the reduced-pressure atmosphere is held by the packing 7. The vacuum container is connected to a vacuum pump via the exhaust port 3. The cooling water is supplied from the cooling water inlet 5 to the anode electrode 4 and the water-cooled body 2 and discharged through the cooling water outlet 6. The inside of the vacuum vessel wall is surrounded by insulating ceramics 9. Anode 4 is DC power supply 1
1 connected. The DC power supply has a mechanism in which a high-frequency high voltage is superimposed on the DC at the time of starting an arc, and when the arc starts stably, the generation of the high-frequency high voltage stops and only the DC voltage is applied. Since this mechanism is a known technique, detailed description is omitted in FIG.

An alumina pipe was used as the material of the ceramics 9. No treatment was previously performed on the ceramic surface, and no conductive film was formed on the surface. Once the vacuum arc started, the inner surface of the ceramic was vaporized from the metal surface and became conductive, and the arc ignition characteristics changed.Therefore, the experiment was performed by replacing the ceramic pipe with a new one for each measurement. . Several DC power supplies with different no-load voltages were prepared, but all were constant current DC power supplies with an arc current value of 100A.
And the measurement was performed. The high frequency voltage superimposed on the DC voltage is generated by a commercially available high frequency generator used at the time of starting the TIG welding arc. After the inside of the vacuum vessel was evacuated to 50 Pa by the vacuum evacuation apparatus 10, a high-frequency high voltage was applied to a no-load DC voltage to determine whether arc ignition was possible.

The vertical axis in FIG. 1 shows the number of times the arc has been started by applying the high frequency 20 times under each no-load voltage condition, and shows the probability of the start success as a percentage. The possibility of arc ignition is fairly stochastic, and it does not mean that a power source with a low no-load voltage used in the conventional method cannot ignite at all, but it can be ignited with a low probability. It has been found that when the no-load voltage exceeds 100 V, it can be considered that the arc can be started substantially stably.

[0014]

【Example】

Example 1 A hot-rolled steel sheet covered with black scale was used as a treated metal material, and the scale of the hot-rolled steel sheet was removed using a metal surface local treatment apparatus using a vacuum arc shown in FIG. The arc power supply used is a constant current operation type power supply capable of generating and applying a high frequency high voltage at the time of arc start at a no-load voltage of 180V. The inner wall of the vacuum vessel that creates a vacuum atmosphere locally is made of alumina ceramics. The inner surface of the alumina ceramics is not pre-treated such as conductive coating.

After the pressure inside the vacuum vessel is reduced to 50 Pa by a vacuum exhaust device, the arc current is set to 100 A,
When the anode and cathode hot-rolled steel material to be treated were connected to an arc power source and a voltage obtained by superimposing a high-frequency high voltage on a no-load DC voltage was applied, the arc started stably and the scale of the hot-rolled steel material was removed. did it. The maintenance voltage of the vacuum arc during the descaling period was 32V.

Example 2 A hot-rolled steel sheet covered with black scale was used as a metal material to be treated, and the scale of the hot-rolled steel sheet was removed using a metal surface treatment apparatus using a vacuum arc shown in FIG. The arc power supply used is a constant current operation type power supply capable of generating and applying a high frequency high voltage at the time of arc start at a no-load voltage of 180V. The pressure inside the vacuum vessel 12 is reduced by the vacuum exhaust device 10 to 50 Pa, the arc current is set to 100 A, the anode 4 and the hot-rolled steel material 1 to be treated as the cathode are connected to the arc power supply 11, and no load is applied. When a voltage obtained by superimposing a high-frequency high voltage on a DC voltage was applied, the arc started stably and the scale of the hot-rolled steel could be removed. The maintenance voltage of the vacuum arc during the descaling period is 31
V.

[0017]

According to the apparatus of the present invention described above, the start of the arc is simple and reliable, and the cleaning and heat treatment of the metal surface by the vacuum arc can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the start of a vacuum arc and the no-load voltage of a power supply.

FIG. 2 is a configuration diagram of a metal surface local treatment apparatus using a vacuum arc surrounded by ceramic inner wall surfaces.

FIG. 3 is a configuration diagram of a metal surface treatment apparatus using a vacuum arc according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Metal to be processed 2; Vacuum container water cooling body part 3; Vacuum exhaust port 4; Anode 5; Cooling water supply inlet 6; Cooling water discharge outlet 7; Packing 8; Vacuum container hem 9; Ceramics 10; ; Arc power supply 12; Vacuum container

────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁷ Identification symbol FI C23F 4/00 C23F 4/00 A (56) References JP-A-64-42574 (JP, A) JP-A-3-134156 ( JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C23G 5/00 C21D 1/773 C21D 1/82 C23F 4/00

Claims (2)

(57) [Claims] 1. A electrode, the vacuum vessel, the metal surface treatment apparatus according to the vacuum arc consisting of the arc power supply and exhaust system, and the machine structure capable of superimposing a high-frequency high voltage to a DC voltage as the arc power supply, an arc is started in a stable high-frequency high Electric
A mechanism that stops the generation of pressure and becomes only a DC voltage ,
A metal surface treatment apparatus using a vacuum arc, comprising a power supply having a no-load voltage of 100 volts or more. 2. A metal surface treatment apparatus using a vacuum arc comprising an electrode, a vacuum vessel, an arc power supply and an exhaust device, wherein the vacuum vessel incorporates an electrode and has a sealing material for providing adhesion to a member to be treated. in metal surface topical treatment apparatus according to the vacuum arc is cup-shaped vacuum vessel having a section, a machine structure capable of superimposing a high-frequency high voltage to a DC voltage as the arc power supply, an arc is started in a stable high-frequency high
A metal surface treatment apparatus using a vacuum arc, comprising: a mechanism for stopping generation of voltage and providing only a DC voltage ; and a power supply having a no-load voltage of 100 volts or more.